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How Machines Do Work What is a machine? A device that allows you to do work in a way that is easier. Ways machines make work easier 1. Increasing the force Example: A car jack multiplies your force by having it over a greater distance. 2. Increasing the distance Example: A ramp allows a person to use less force to lift a box on to the back of a truck 3. Changing Direction Example: A weight machine or raising a flag up a flagpole Difference between input and output force? Input Force – The force you exert on the machine. Output Force – The force the machine exerts on an object. Example: For a shovel – input your force on the shovel output the force the shovel exerts on the dirt Mechanical Advantage The number of times a machine increases a force exerted on it. Formula: MA= output force input force Example: Suppose you exert an input force of 10N on a handheld can opener, and the can opener exerts an output force of 30 N on a can. What is the mechanical advantage of the can opener? M.A. and how machines make work easier • Increasing force: M.A. > 1 • Increasing Distance: M.A. < 1 • Changing Direction: M.A. = 1 Ideal vs. Real Machines For IDEAL machines, the output is always equal to the input. For REAL machines (the ones we’re familiar with), the output is always Less than the input work because of _________.